The IT staff maintain several machines in Cahill 249 (public computer room) and 235 (Astronomy visitor room). You must have a @astro account to access the linux machines in these offices. An account can be requested here.
We have a Windows (taurus.caltech.edu) and a Mac (auriga.caltech.edu) in 249 for public use. These machines are mainly used to print posters. Both these machines have a guest account named as "ADPF Guest". Please contact help@astro at x4006 in Cahill 227 for the password.
There is a scanner attached to auriga.caltech.edu. For more information on how to use the scanner, please see Using the scanner.